[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[C:8]1[C:12]([C:13]#[C:14][C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)=[C:11]([NH2:21])[N:10]([CH3:22])[N:9]=1.[N:23]([O-])=O.[Na+].[ClH:27]>O>[Cl:27][C:13]1[C:14]([C:15]2[CH:16]=[CH:17][CH:18]=[CH:19][CH:20]=2)=[N:23][N:21]=[C:11]2[N:10]([CH3:22])[N:9]=[C:8]([C:3]3[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=3[Cl:1])[C:12]=12To a cooled (cooling bath −15° C.) stirred suspension of 3-(2-chlorophenyl)-1-methyl-4-(phenylethynyl)-1H-pyrazol-5-amine (136 mg, 0.44 mmol) in conc. HCl (3.7 mL) was added a solution of sodium nitrite (34 mg, 0.49 mmol) in water (0.3 mL). After 5 min, the cooling bath was removed and the reaction mixture was stirred at room temperature for 1 h. The reaction was cooled again (0° C.) and poured onto a sat. NaHCO3 solution. Ethyl acetate was added and pH was adjusted to 7-8 with sat. NaHCO3. The aqueous phase was extracted with ethyl acetate and the organic phases combined, dried over MgSO4, filtered and evaporated. Crude material was purified by column chromatography (silica gel, gradient 0 to 4% ethyl acetate/CH2Cl2) yielding Compound 37 as a solid (47 mg).
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